Therefore, the crucial role of FoxP3+ Tregs in endometrial receptivity and embryo implantation [30,40,41] dictates the need for alternative therapeutic approaches to support endometrial FoxP3 activation and the periconceptional expansion of the CD4+CD25+ Tregs in infertile women [27], especially those with PCOS. The gene discussed is FOXP3; the disease is polycystic ovary syndrome.